Title:
CONSTANT CURRENT CIRCUIT
Document Type and Number:
Japanese Patent JPS57106915
Kind Code:
A
Abstract:
PURPOSE:To obtain an output current which is stable against variation in electric power while simplifying a starting circuit, by providing an output transistor (TR) and a shunting TR. CONSTITUTION:As a power voltage Vcc rises and a TRQ2 is nearly saturated, a current i2 increases. At this time, a potential at a point B drops, so a shunting TRQ6 is activated to shunt part of a current, flowing from a point A to the base of the TRQ2, to an earth GND. As a result, the current flowing to the TRQ2 decreases, so that the potential at the point B rises. Said succeeding operations are performed instantaneously through a negative feedback path which uses an output TRQ5, so the potential at the point B is held constant eventually without variation in voltage Vcc. This means that the currents of current mirror TRs Q3 and Q4 are constant, so a current i3 appearing at a terminal T1 is constant without reference to the variation in voltage Vcc.
Inventors:
ONO AKIHIKO
SANO YOSHIAKI
SANO YOSHIAKI
Application Number:
JP18308080A
Publication Date:
July 03, 1982
Filing Date:
December 24, 1980
Export Citation:
Assignee:
FUJITSU LTD
International Classes:
G05F3/26; G05F3/30; (IPC1-7): G05F1/56